Research data management has become an important part of any large research study or program project study. The development of powerful and affordable PC computers has revolutionized the ability of researchers to collect, compile and maintain a large quantity of data in any research study. However, to maintain data that accurately reflects reality in a timely and usable manner requires a systematic handling of this data from the collection of the initial data to the final electronic storage of information. The specific aims of the Data Management Core (DMC) are: 1) develop a data management system that systematically acquires, manipulates, documents and stores the research data of the program project in a computer system; 2) create and maintain a set of activities for handling data such as data collection, data entry, data editing or cleaning and backing up of the data to accomplish the objectives of the data management system for the program project; 3) develop and maintain activities and procedures to evaluate or monitor the ongoing data management process for the program project. DMC activities will include development of data forms, study number assignment and randomization, development of computer data entry systems and data sets, data entry, data integrity, data monitoring and reporting, data manipulation and analysis, data backup, security and archiving, and documentation. The primary focus of this core will be to provide data management assistance in accomplishing the scientific research goals of the program project.